Table of Contents

1. George Berkeley: From Introspection to Idealism
2. Brain in a Vat
3. No Material Objects
4. Outline of Berkeley’s Arguments
5. First Featured Argument
6. Second Featured Argument
7. Third Featured Argument
8. Arguments that physical objects don’t have secondary qualities
9. Arguments that physical objects don’t have primary qualities
10. Arguments for Idealism
11. Arguments against the theory of material objects (TOMO), that sense-perceptions are caused by material objects that resemble them
12. Berkeley’s Replies to Objections

George Berkeley:
From Introspection to Idealism

Brain in a Vat

No Material Objects

• Locke had distinguished between perceptions of things and the cause of the perceptions.
  • Primary Qualities
    • The weight of a tomato is caused by its mass
    • So the weight we feel holding a tomato resembles the physical tomato.
  • Secondary Qualities
    • A tomato’s color is caused by light waves bouncing of the tomato, entering the eye, and reacting with photoreceptor cells in the retina, which triggers nerve impulses that travel to the visual centers of the brain.
    • So, the red we see does not resemble the physical tomato.
• Berkeley agrees with Locke’s distinction between primary and secondary qualities.  Indeed, he provides an argument better than any of Locke’s.
• But Berkeley goes much further. He argues that we have the experience of perceiving material objects without there being any.
• Like the brain-in-a-vat scenario, you have the same experience of perceiving physical objects as you would have were you actually perceiving them.

Outline of Berkeley’s Arguments

• Arguments that physical objects don’t have secondary qualities
  • Heat and Pain
  • Relativity of Secondary Qualities
• Arguments that physical objects don’t have primary qualities
  • Relativity of Primary Qualities
  • Extension implies color
• Arguments for Idealism
  • Direct Proof
  • Esse est percipi (to be is to be perceived)
• Arguments against the theory of material objects (TOMO)
  • TOMO leads to skepticism
  • TOMO postulates a mystery
  • TOMO leads to contradiction
  • TOMO’s idea of resemblance is incoherent
• Berkeley’s Replies to Objections:
  • Objection: If physical objects exist only when perceived, they would continually pass into and out of existence.
    • Reply: Objects are always perceived by God
  • Objection: If physical objects exist only in the mind, how can they appear three-dimensional?
    • Reply: We infer distance from a combination of sensations, such as sight and touch.
  • Objection: If sense-perceptions are not caused by material objects, what causes them?
    • Reply: God

First Featured Argument

• Overall Argument
  • If tomatoes were red, different species of animal would see the same red color.  But they don’t. So tomatoes aren’t red.
• Berkeley
  • “Is it not therefore highly probable those animals in whose eyes we discern a very different texture from that of ours, and whose bodies abound with different humors, do not see the same colors in every object that we do? From all which, should it not seem to follow that all colors are equally apparent, and that none of those which we perceive are really inherent in any outward object?” (First Dialogue, 1713)
• Are Dogs Really Color-Blind? (Britannica)
  • “In humans, each cone perceives, roughly, the wavelengths of light that correspond to red, green, and blue-violet. By overlapping and mixing the spectrum of colors that the three human cones perceive, we are capable of seeing a wide variety of colors.”
  • “In dogs, however, the two color receptors in the eyes perceive wavelengths of light that correspond to blue and yellow, meaning that dogs see only in combinations of blue and yellow. So instead of bright red roses, dogs likely see yellowish brown petals, and lively green grass looks more dehydrated and dead.”
• Argument
  • Humans see tomatoes as red whereas dogs likely see them as yellowish-brown.
  • If tomatoes have a particular color, it’s possible that humans correctly see tomatoes as red, but dogs misperceive them as yellowish-brown.  But it’s equally possible that dogs correctly see yellowish-brown tomatoes and humans misperceive them as red. In short, if tomatoes have a particular color, there would be no way of finding out what color that is.
  • Tomatoes therefore don’t have any particular color.  What color a species sees depends on
    • the molecular structure of the tomato’s surface (which determines the wavelength of reflected light)
      • and
    • the sensory organs of the species.
  • Thus, tomatoes aren’t red or any other color.

Second Featured Argument

Esse est percipi (Below)

Third Featured Argument

Berkeley’s Argument for the Existence of God (Below)

Arguments that physical objects don’t have secondary qualities

• Heat and Pain
  • A high degree of heat is an intense pain.  Physical objects don’t experience pain. Therefore, a high degree of heat cannot exist in physical objects.
• Relativity of Secondary Qualities
  • If physical objects possessed secondary qualities, everyone perceiving the same object would perceive the same secondary quality. Such is the not the case.
    • Same person
      • What is hot to one hand may be cold to the other
    • Different people
      • What is sweet to one person may be bitter to another
    • Different species
      • What is red for one species may be a shade of gray for another species.
      • “Is it not therefore highly probable those animals in whose eyes we discern a very different texture from that of ours, and whose bodies abound with different humors, do not see the same colors in every object that we do? From all which, should it not seem to follow that all colors are equally apparent, and that none of those which we perceive are really inherent in any outward object?” (First Dialogue)

Arguments that physical objects don’t have primary qualities

• Relativity of Primary Qualities 
  • Like secondary qualities, extension and motion are relative to the perceiver
    • “Large and small and swift and slow, being entirely relative and changing as the frame or position of the organs of sense varies, exist only in the mind. Therefore extension in material objects is neither great nor small; and motion neither swift nor slow.” PHK 11
  • The shape and size of a physical object appear different to people at different places and to animals of different species
    • “Now, why may we not as well argue that figure and extension are not patterns or resemblances of qualities existing in Matter, because to the same eye at different stations, or eyes of a different texture at the same station, they appear various, and cannot therefore be the images of anything settled and determinate without the mind?”  PHK 14
  • Whether something is moving fast or slow is relative to different beings because fast and slow are relative to the speed of the succession of ideas in the mind
    • “Is it not as reasonable to say that motion is not without the mind, since if the succession of ideas in the mind become swifter, the motion, it is acknowledged, shall appear slower without any alteration in any external object?” PHK 14  
• Extension implies color
  • Anything that is extended in space must have a color. So there can’t be an object having primary qualities but no secondary qualities.
    • “For my own part, I see evidently that it is not in my power to frame an idea of a body extended and moving, but I must withal give it some color or other sensible quality which is acknowledged to exist only in the mind. In short, extension, figure, and motion, abstracted from all other qualities, are inconceivable.” PHK 10

Arguments for Idealism

• Direct Argument
  • We perceive ordinary objects (tomatoes, stones, books, etc.)
  • We perceive only ideas
  • Therefore, ordinary objects are ideas.
• Esse est percipi (to be is to be perceived)
  • The idea of an unperceived physical object is inconceivable and therefore self-contradictory.  Thus, existence is the same thing as being perceived
  • Try imagining an unperceived object, a Saguaro cactus in the desert, say.  Is it unperceived? Not at all. You’re perceiving the imagined cactus. Likewise for anything else you try to imagine unperceived.  It’s thus impossible to conceive of an unperceived object. To be is to be perceived.
  • “When we do our utmost to conceive the existence of external bodies, we are all the while only contemplating our own ideas. But the mind taking no notice of itself, is deluded to think it can and does conceive bodies existing unthought of or without the mind, though at the same time they  are apprehended by or exist in itself. A little attention will discover to any one the truth and evidence of what is here said, and make it unnecessary to insist on any other proofs against the existence of material substance.” PHK 23

Arguments against the theory of material objects (TOMO),
that sense-perceptions are caused by material objects that resemble them

• TOMO leads to skepticism
  • Knowledge of material objects beyond the senses must be by sense or reason.  But the senses inform us only of sense-perceptions, nothing beyond. And reason reveals no logical connection between sense-perceptions and material objects, since the former can occur without the latter. Were there material objects beyond the senses, therefore, their existence could not be known.
• TOMO postulates a mystery
  • According to TOMO, physical objects cause sense-perceptions.  When a person sees a tomato, for example, light bounces off the tomato, enters the eye, hits the retina and makes visual neurons fire. Signals are transmitted by the optic nerves to the visual cortex in the back of the brain. 
  • And then the inexplicable happens: the person experiences tomato sensations. How a physical event causes a mental event is incomprehensible.  TOMO thus explains perception by postulating a mystery.
  • “The existence of external bodies affords no explication of the manner in which our ideas are produced.–But, though we might possibly have all our sensations without them, yet perhaps it may be thought easier to conceive and explain the manner of their production, by supposing external bodies in their likeness rather than otherwise; and so it might be at least probable there are such things as bodies that excite their ideas in our minds. But neither can this be said; for, though we give the materialists their external bodies, they by their own confession are never the nearer knowing how our ideas are produced; since they own themselves unable to comprehend in what manner body can act upon spirit, or how it is possible it should imprint any idea in the mind”. PHK 19
• TOMO leads to a contradiction
  • Due to differences in the structure of the eye, different species see things differently.  Thus what humans see as red another species might see as gray. Red and Gray cannot therefore be properties of objects.  So material objects don’t have color.
  • But material objects are extended in space and it’s impossible to conceive of an extended object with no color.  Therefore, material objects have color.
  • Were TOMO true, therefore, material objects would have color and not have color.
• TOMO’s idea of resemblance is incoherent
  • According to TOMO sense-perceptions resemble the material objects that cause them.  But “an idea can be like nothing but an idea; a color or figure can be like nothing but another color or figure. If we look but never so little into our thoughts, we shall find it impossible for us to conceive a likeness except only between our ideas.” (PHK 8)

Berkeley’s Replies to Objections

• Objection: If objects exist only when perceived, they would continually pass into and out of existence
  • Reply:
    • Objects are always perceived by God
    • “The table I write on I say exists, that is, I see and feel it; and if I were out of my study I should say it existed–meaning thereby that if I was in my study I might perceive it, or that some other spirit actually does perceive it.” PHK 3
    • “Whence I conclude, not that they have no real existence, but that, seeing they depend not on my thought, and have all existence distinct from being perceived by me, THERE MUST BE SOME OTHER MIND WHEREIN THEY EXIST. As sure, therefore, as the sensible world really exists, so sure is there an infinite omnipresent Spirit who contains and supports it.” 3D
• Objection: If objects exist only in the mind, how can they appear three-dimensional?
  • Reply:
    • “Distant things in a dream are actually in the mind. Also, we do not directly perceive distance while we are awake. We infer distance from a combination of sensations, such as sight and touch. Distant ideas are ideas that we could perceive through touch if we were to move our bodies.” (PHK 44)
• Objection: If sense-perceptions are not caused by material objects, what causes them?
  • Reply (Berkeley’s Argument for the Existence of God)
    • Since material objects don’t exist, there are only three possible causes of my perceptual experiences:
      • Myself
      • Other mental phenomena of mine
      • Some spirit other than myself.
    • Myself
      • I can’t be the cause of my perceptual experience because sense-perceptions are involuntary and therefore not under my control.
    • Other mental phenomena of mine
      • “All our ideas, sensations, notions, or the things which we perceive, by whatsoever names they may be distinguished, are visibly inactive–there is nothing of power or agency included in them. So that one idea or object of thought cannot produce or make any alteration in another.” PK 25
    • By process of elimination, my perceptual experiences must be caused by another spirit. The most plausible hypothesis is God.